Temperature-responsive throttling valve



March "25, 1952 c, D, MacCR'CKEN ETAL 2,590,112

TEMPERATURE-RESPONSIVE THRoTTLINc VALVE original Filed Jam;l 13, 1949 Arran/Ey:

Patented Mar. 25, 1952 TEMPERATURE -RESPNSIVE THRQTTLING VALVE Calvin l). MacCracken, Tenay, N. J., and Charles W. Wood, Dayton, Ohio, assignors to Jet-Heet, Inc., Englewood, N. J., a corporation of New York @riginal application `l'anuary 13, 1949, Serial No.

Divided and this application November 13, 1950, Serial No. 195,202

6 Claims.

This invention relates to a temperature-responsive throttling valve which is particularly, but not exclusively, useful in connection with liquid fuel control systems employing mechanical atomizers or spray nozzles of the return-now type, for example, a liquid fuel control system designed to supply a liquid fuel such as fuel oil, gasoline, kerosene, alcohol, etc. at a low rate, for example, at the rate'ofl A to 2 gallons per houl` which is suiilcient for heating purposes in most house-heating and certain other systems. The term fuel oil as hereinafter ,used isv intended tov include any liquid fuel.

This application is a division of our co-pending application Ser. No. 79,773, led JanuaryA 13, 1949.

Mechanical atomizers or spraynozzlesof the return-flow type are characterized by a central whirling chamber` to which the fuel-oil is supplied, at substantially constant pressure, through tangential passages, thereby imparting whirling motion to the oil in said chamberl some of which is discharged in a spray through a small orifice and some. of which leaves the` whirling chamber through an'orice or` orifices communieating with a pipethrough which the oil returns to the supply source. The quantity of fuel-oil emitted from an atomizer of that type in the form of a spray may be` controlled by regulating the flow of oil through the return pipe by providing therein a valve which is'manuallyor otherwise operated. These return-flow typev atomizers are particularly useful at low-fuel-oilv deliveryvv rates, because their larger total;` fuel-oil i'low requires greaterv internal dimensions and givesa` coolingv and scouring action, all of which greatly reduces thev tendencyk to plug-up with dirtorfuel-oil residue.v

So long as the temperature of the fuel-oil in the atomizer remains substantially constant, the viscosityA ofr the oil in theatomizer` is substantially constant, and the quantity of oil` supplied-from the atomizer in the form of a spray for-combustionpurposeswill not varyv substantially if thepressure in the return pipe isV held constant. However, in many heating systems of the-type mentioned, the temperature andl viscosity of thefuel-oil in the nozzle will vary considerably during the operation of the heating unit'. Such variations-may be due to variations inthe temperature of the fuel-oil inY the suppl'ytanlr, particularly'when the tank` isl located out-'ofdoors;;but; inmany'cases, the variations ink the temperature and,` viscosity ofthe fuel'ecil lin the nozzle are largely due to variations in the temperature of the nozzle itself due to the fact that it is alternately heated up and cooled off. Such variations in the temperature and viscosity of the fuel-oil in the atomizing nozzle may cause considerable variation in the quantity of oil supplied by the atomizer as a spray for combustion purposes. It is incorrect, however, to assume that4 the quantity of fuel-oil emitted by an atomizer of the type mentioned is greater when the oil in the atomizer has a high temperature and low viscosity, than when it has a low temperature and high viscosity. In fact, the contrary is true; and it is our-belief that this is due to the fact that, when thel temperature of the oil inthe atomizer is high and its Viscosity is low, more rapid whirling of the oil within the atomizer and decreased resistance in the return passage, which is larger than the spray orifice, result in a decrease of the total amount of oil which flows out of the spray orifice.

The principal object of the present invention is to provide a temperature-responsive throttling valve, adapted for use in the return pipe from an atomizer of the return-ow'type, to so control the flow of fuel oil through the return pipe that the quantity of oil emitted as a spray by the atomizer, under variations of the temperature and viscosity of the oil in the nozzle, will be substantially constant.

Another object of the invention is to provide a throttling valve which will prevent bleeding of the oil from the return pipe back into the atomizer and out of the spray opening therein, when the system is shut down by cutting olf the supply of oil to the atomizer. These objects are attained by the novel throttling valve hereinafter described, which automatically responds to variations in the temperature of the oil passing through said device, and exerts on the oil flowing therethrough a throttling elfect which is greater at high temperatures of the oil than at low temperatures thereof and which, upon shutting off the oil supply, prevents any back flow of fuel to the atomizer.

The invention will be understood from the following. description taken in connection with the accompanying drawing in which Fig. 1 is a diagrammatic representation of a fuel-oil control system in which the novel throttling valve of the. invention may be employed; Fig. 2 is a sectional elevation ofthe novel throttling Valve; and Fig. 3is a sectional elevation, on an enlarged scale, showing the construction of the temperature responsive element of the throttling valve.

Referring to Fig. 1 of the drawing, a mechanical fuel-oil atomizer 4 of the return-flow type is shown as supplied with fuel-oil from an oil tank 6 at a substantially cons-tant pressure b-y an oil pump 8; and the return-flow outlet of the atomizer 4 is connected through a throttling valve I (illustrated in Fig. 2 and hereinafter described) to the oil tank 6. As will hereafter appear, the throttling valve I6, through which flows the oil returning from the atomizer 4, is characterized by the fact that it contains an element responding to the temperature of the oil and functioning to increase and decrease the throttling effect of the valve on the oil flowing through it, with the rise and fall of the temperature of the oil. That is, after the throttling valve I6 has been set so as to exert a throttling effect on the returning oil such that the atomizer will spray fuel-oil at a desired rate, the throttling valve I0 will continue to function, in response to varying temperatures of the oil, so that the throttling effect of the valve will maintain substantially constant the quantity of oil sprayed by the atomizer.

Referring now to Fig. 2, in which the construction of the novel throttling valve I0 is illustrated, it will be evident that it has a casing consisting of the upper part I2 and the lower part I4 which parts have cooperating flanges which are bolted together by the bolts I5. A iiexible circular diaphragm I6, of neoprene or any other suitable material, the edge of which is clamped between the flanges of the casing parts I2 and I4, is thus mounted within the casing and serves as a movable valve member. The lower casing part I4 is provided with a chamber I8 having a fuel-oil inlet opening 26 and surrounded by a circular lip 22 which cooperates with the diaphragm I6 and serves as a valve seat. The casing part I4 is also provided with a circular trough 23 located outside of and concentric with said lip 22 and this trough is provided with an oil outlet opening 24. Cooperating with the diaphragm I6 is a backing member consisting of a circular plate 26 having a hub 2'I provided with a central hole through which is threaded a bolt 28 having a nut 3D cooperating therewith and with the hub 21 of the plate 26. It will be obvious from the drawing that the plate 26 forming part of the backing member cooperates with the upper side of the diaphragm I6 and that said plate 26 extends outwardly to the vicinity of the lip 22 and preferably to approximately the outer edge of said lip. Thus the plate 26 confines the upward flexing of the diaphragm I6 to that portion of the latter which is between the outer edge of the plate 26 and the casing anges between which the edge of the diaphragm I6 is clamped. In Fig. 2, the space shown between the diaghragm I6 and the lip 22, and the exing of the diaphragm I6 are both exaggerated, in order to aid in understanding that in the functioning of the throttling valve the oil ows from the chamber I6 over the lip 22 into the trough 23. Since diaphragm I6 is fastened to plate 26 only at the center, nothing holds the diaphragm off its seat 22 except the pressure of the oil flowing betwen the seat and the adjacent portion of the diaphragm, and when there is no pressure cr the slightest negative pressure the diaphragm immediately seals against its seat. Since there is only a thin film of oil separating them, practically no oil is displaced when such sealing occurs.

Located within the upper casing section I2 is a. coiled spring 32 which at its lower end cooperates with the plate 26 of the backing member and at its-upper end with a disc 34 engaged by a. screw 36 threaded through a hole in the top of the casing member I2. 1t will be understood that the screw 36 may be adjusted to vary the pressure exerted by the spring 32 upon the backing member which cooperates with the diaphrgam I6.

Located within the chamber I8 in the lower casing member I4, is a temperature responsive means which is illustrated on an enlarged scale in Fig. 3. This temperature responsive means consists of two bi-metal discs spaced apart and secured to one another at their edges by a ring 40. As is best shown in Fig. 3, each of the discs of the temperature responsive device is composed of two layers 42-43 and 44-45 of metal welded together, said layers having diierent thermal coefcients of expansion. The layers 42 and 44 having the lower coeflicients of expansion are located on the outside, and the layers 43 and 45 having higher coefficients of expansion are located on the inside of the temperature responsive means. Said discs (which are flat at room temperature with no compression but which are shown in Figs. 2 and 3 under initial compression from the force of the spring 32) buckle toward one another at higher temperatures and away from one another at lower temperatures. As shown in Fig. 2, the casing member I4 is provided in the bottom of the chamber I8 with an abutment 46 having an upwardly extending central portion 48; and the discs of the temperature responsive means just described are provided at their `centers with openings adapted to receive the upwardly extending portion 48 of the abutment 46. In this way, the temperature responsive means is centered in the chamber I8. The bolt 28 is provided at its lower end with a cupshaped head 56 the edges of which are adapted to cooperate with the temperature responsive means. The abutment and bolt head 56 limit the compression of the temperature responsive means under the force of the spring 32 so that the discs will not be overstressed by reason of the fact that the cup in head 50 is made of such depth that the top of portion 48 strikes the bottom of the cup and limits the compression. The inlet opening 26 in the casing member I4 may be provided with a check valve 52, as shown in Fig. 2, but this check valve may be omitted if desired.

The mode of operation of the throttling valve will be understood with the aid of Fig. 2. The fuel oil, returning from the atomizer 4 through the opening 26, fills the chamber I8 and iiows over the lip 22 into the trough 23 and from that trough flows out through the opening 24 and on to the fuel-oil tank 6 or instead to the intake side of the pump if desired. As long as the oil remains at the same temperature, cooperation of the diaphragm I6 with the lip 22 will exert on the oil a constant throttling effect. Upon a rise in the temperature of the oil flowing through the chamber I8, and bathing the temperature responsive element, the discs in the temperature responsive element will ex toward one another, thereby increasing the net effective pressure exerted by the spring 32 upon the backing member and the diaphragm I6, and thus increasing the throttling effect on the oil flowing between the diaphragm I6 and the lip 22. The action of the thermal responsive element is not actually to raise or lower the diaphragm from its seat but to counterbalance the spring pressure on the diaphragm, to a greater or less extent, which opposes the pressure of the fuel in the return ow pipe. If, how,-

ever,'the temperature of the oil decreases, the

discs; of the temperature responsive. elementuwill flex: away,l from one` another,l thus; decreasing` the;

perature; of the, oil, thatlisvvitli thea decreasing. and increasing, of` theviscosity of theV oil, with the` resultlthatgthe atomizer will spray oil atsubstan'- tially a constant'rate, even thoughA the viscosity of the oil passing. through the atomizer varies considerably. As` has beenV stated, Fig. 2 represents in exaggerated form the space between the diaphragm i6. and the lip 22 and this space is in fact very small at all times. Virtually, the oil squeezes through between the seat 22 and the diaphragm I6 ina film of almost unmeasurable thinness againstthe neteffective' pressure of the spring.

When a fuel-oil control system of the kind-illustrated'in Fig. 1 is shutdown bycutting offthe supply of oil to the spray nozzle 4, it is important that no oil be allowed to bleed back into the atomizer 4 from the return pipe. The throttling valve shown in Fig. 2 prevents such backflow into the oil atomizer, due to the fact that when the supply of oil to the atomizer is cut off the pressure of the oil in the return-now pipe drops, and the outer portion of the diaphragm IG instantly flexes into contact with the lip 22, thereby preventing back-flow toward the atomizer of the fuel-oil trapped in the return pipe and in the throttling valve. Because the flexing of the diaphragm I6 displaces only a minute quantity of oil from between the diaphragm I6 and the lip 22, the result is that substantially no back-flow of oil to the atomizer occurs. assists in preventing such back-flow of oil but, as has been mentioned, this check valve is unnecessary under most conditions of operation because the diaphragm, in the absence of a defect, forms a complete seal by itself.

It will be understood that, when used With different oils having varying viscosities and with different types of return-flow nozzles having varying pressure-flow characteristics, the temperature responsive means will have to be changed accordingly. This is best done by varying the thickness of the bi-metallic `discs which is normally about .025 to .030 of an inch. Also, if less temperature compensation is required, the thickness of the discs should be less and vice versa. In this disclosure two bi-metallic elements have been used in order to reduce the spring rate, that is, the rate of change of force exerted by the bimetallic elements as they are further compressed. This is desirable in order to reduce sensitivity to dimensional tolerances. It should be understood that this effect can be accomplished in other ways or may not be necessary, and that a single bimetallic element with corresponding changes in cooperating parts can be used.

' What is claimed is:

1. A temperature-responsive throttling valve for liquid fuel subject to variations in temperature and adapted to increase the throttling effect with increase in temperature comprising, a casing having a chamber, a valve seat surrounding said chamber, a flexible diaphragm overlying said seat and forming a wall of said chamber, said casing having a fuel inlet communicating with said chamber and a fuel outlet communicating with The check valve 52 i thespace outside saidfvalve seat, resilient mea-ns positioned on the oppositeside of thediaphragm;

from vsaid chamber urging-said diaphragmtoward said seat, and a thermally responsive pressure element in said chamber bathed` by the fuel passing therethrough andacting in opposition to saidl resilient meansto increase and decrease the closing pressureon said. diaphragm according, respectively, to an increase or decrease in temperaturei of` the fuel in. said'chamber.

2. A temperature-responsive. throttling. valve forliquid fuel subjectto variations in temperature and adapted to increasethe throttling effect' with increase in temperaturecomprising, a casing havingachamber, a valveseat surrounding: said chamber, a flexible diaphragm overlying said seat andforming a Wall of` said chamber, said casing,

having a fuel inlet communicating with said chamber and a fuel outlet communicating withv the spaceoutside said valveseat, a backing member positioned oni theopposite side of the dia-- phragmfrom said chamber, a. spring. acting on said member and urging said diaphragm toward said seat', and a thermally responsive pressure element vin said chamber bathed by the` fuel passing therethrough and acting in opposition to said spring to increase and decrease the closing pressure on said diaphragm according, respectively, to an increase or decrease in temperature of the fuel in said chamber.

3. A temperature-responsive throttling valve for liquid fuel subject to Variations in temperature and adapted to increase the throttling effect- With increase in temperature comprising, a casing having a chamber, a valve seat surrounding said chamber, a exible diaphragm of rubberlike material overlying said seat and forming a wall of said chamber, said casing having a fuel inlet communicating with said chamber and a fuel outlet communicating with the space outside said valve seat, a backing member positioned on the opposite side of the diaphragm from said chamber and overlying said seat, a spring acting on said backing member and urging said diaphragm toward said seat, and a thermally responsive pressure element in said chamber bathed by the fuel passing therethrough and acting in opposition to said spring to increase and decrease the closing pressure on said diaphragm according, respectively, to an increase or decrease in temperature of the fuel in said chamber.

4. A temperature-responsive throttling valve for liquid fuel subject to variations in temperature and adapted to increase the throttling effect with increase in temperature comprising, a casing having a chamber, a valve seat surrounding said chamber, a flexible diaphragm overlying said seat and forming a wall of said chamber, said casing having a fuel inlet communicating with said chamber and a fuel outlet communicating with the space outside said valve seat, resilient means positioned on the opposite side of the diaphragm from said chamber urging said diaphragm toward said seat, and a thermally responsive bi-metal pressure element in said chamber bathed by the fuel passing therethrough adapted to expand with a decrease in temperature and acting in opposition to said resilient means to increase and decrease the closing pressure on said diaphragm according, respectively, to an increase or decrease in temperature of the fuel in said chamber.

5. A temperature-responsive throttling valve for liquid fuel flowing under pressure at a low rate and subject to variations in temperature adapted to vary the throttlng effect on said fuel with variations in temperature of the fuel, comprising, a casing having a chamber, a circular upstanding valve seat surrounding said chamber, a exible rubberlike diaphragm overlying said seat and forming a Wall of said chamber, said casing having a fuel inlet communicating with said chamber and a fuel outlet communicating with the space surrounding said valve seat, a spring positioned on the opposite side of the diaphragm from said chamber and urging said diaphragm toward said seat, and a thermally responsive pressure element in said chamber comprising a pair of bi-metal discs secured together at their edges and bathed by the fuel passing therethrough and arranged to oppose said spring to increase a-nd decrease the pressure of said diaphragm against said seat according, respectivelly, to an increase or decrease in temperature of the fuel in said chamber.

6. In a temperature-responsive throttling valveV of centrally perforated bi-metal discs secured together at their edges, said casing having a chamber in which is a centrally located abutment having a reduced portion positioned in the perforations in said discs and a cup-shaped member surrounding said reduced portion With its edge engaging one of said discs and held in contact therewith by said spring and having a stem extending through said backing member, whereby engagement of the end of said reduced portion of the abutment with the bottom of the cup in said cupshaped member limits the compression of said temperature-responsive means by said spring.

CALVIN D. MACCRACKEN. CHARLES W. WOOD.

REFERENCES CITED The following references are of record in the nie of this patent:

UNITED STATES PATENTS Number Name Date 1,220,985 Harter Mar. 27, 1917 1,635,559 Rockwell July 12, 1927 1,788,048 Carnahan Jan. 6, 1931 

